General Anatomy: Pelvis and Perineum

What is the vertebral level of the rectosigmoid junction?

S3

What spinal nerves are involved in the formation of the pelvic splanchnic nerves?

Anterior nerve roots of spinal nerves S2-S4

What forms the sacral nerve plexus?

Lumbosacral trunk (L4-L5)

Anterior rami of S1-S4

What are the structural classifications of the pelvic joints?

Sacroiliac joints

Sacrococcygeal joint

Symphysis pubis

What is the structural classification of the sacroiliac joint?

Synovial joint (plane joint)

What is the structural classification of the sacrococcygeal joint?

Cartilaginous joint

What is the structural classification of the symphysis pubis?

Cartilaginous joint

What ligaments help suspend the sacrum between the two iliac bones?

Sacrospinous ligament

Sacrotuberous ligament

What are the functions of the sacrospinous and sacrotuberous ligaments?

Stabilize the sacroiliac joint and aid in forming the greater and lesser sciatic foramina

What is the effect of the parasympathetic nervous system on micturition?

Stimulates contraction of the detrusor muscle and inhibits the action of the sphincter vesicae. Allows urination.

What is the effect of the sympathetic nervous system on ejaculation?

Initiates ejaculation. Causes active contraction of the bladder neck during ejaculation. Prevents seminal fluid from entering the bladder.

What is the effect of the parasympathetic nervous system on erection?

Produces erection.

What are the branches of the sacral nerve plexus?

Superior gluteal nerve

Inferior gluteal nerve

Nerve to piriformis

Nerve to obturator internus

Nerve to quadratus femoris

Perforating cutaneous nerve

Posterior cutaneous nerve of the thigh

Sciatic nerve (L4-L5; S1-S3)

Common fibular (peroneal) portion

Pudendal nerve

What are the spinal nerve roots of the sciatic nerve?

L4-L5; S1-S3

What are the branches of the lumbar nerve plexus?

Iliohypogastric nerve

Ilioinguinal nerve

Lateral cutaneous nerve of the thigh

Genitofemoral nerve (L1-L2)

Femoral nerve (L2-L4)

Obturator nerve (L2-L4)

Segmental branches

What are the branches of the anterior division of the internal iliac artery?

Umbilical artery

Obturator artery

Inferior vesical artery

Middle rectal artery

Internal pudendal artery

Inferior gluteal artery

Uterine artery

Vaginal artery

What are the branches of the posterior division of the internal iliac artery?

Iliolumbar artery

Lateral sacral arteries

Superior gluteal artery

What are the branches of the external iliac artery?

Deep circumflex iliac artery

Inferior epigastric artery

What is the main branch of the umbilical artery?

Superior vesical artery

What is a branch of the internal pudendal artery?

Inferior rectal artery

What are the branches of the pudendal nerve?

Inferior rectal nerve

Perineal nerve

Dorsal nerve of the penis (or clitoris)

What is the blood supply of the rectum?

Superior rectal artery

Middle rectal artery

Inferior rectal artery

What is the blood supply of the upper half of the anal canal?

Superior rectal artery

What is the blood supply of the lower half of the anal canal?

Inferior rectal artery

What is the blood supply of the urinary bladder?

Superior vesical arteries and inferior vesical arteries. Branches of the internal iliac arteries.

What is the blood supply of the prostate gland?

Branches of the inferior vesical and middle rectal arteries (from the internal iliac artery)

What is the blood supply of the vulva?

Branches of the external pudendal arteries and internal pudendal arteries (each side)

What is the blood supply of the vagina?

Vaginal artery

Vaginal branch of the uterine artery

What is the blood supply of the ovary?

Ovarian artery

What is the blood supply of the clitoris?

Internal pudendal artery

What is the lymphatic drainage of the clitoris?

Directly to the internal iliac lymph nodes, or to the deep inguinal lymph nodes.

What is the nerve supply of the clitoris?

Branches of the pudendal nerve, carry sensory fibers from the clitoris and provide motor supply to the ischiocavernosus muscle.

What is the blood supply to the skin and superficial fascia of the penis?

External pudendal artery

What is the blood supply to the deep parts of the penis?

Internal pudendal artery

Where does the lymph from the skin of the penis drain?

Medial group of superficial inguinal lymph nodes

Where do the erectile bodies of the penis drain lymphatically?

Internal iliac lymph nodes

What is the nerve supply of the penis?

Pudendal nerve – somatic supply to skeletal muscles and skin

Inferior hypogastric plexus – autonomic fibers to smooth muscle of the penis

What are the contents of the superficial perineal space in males?

Root of the penis: bulb and crura

Muscles covering root structures:

- Bulbospongiosus

- Ischiocavernosus

Superficial transverse perineal muscles

Branches of the pudendal nerve

Branches of the internal pudendal vessels

What are the contents of the superficial perineal space in females?

Bulbs of the vestibule + bulbospongiosus muscles

Crura of the clitoris + ischiocavernosus muscles

Superficial transverse perineal muscles

Perineal nerves and vessels

Greater vestibular (Bartholin) glands

What are the contents of the deep perineal space in males?

Intermediate (membranous) urethra

Part of the external urethral sphincter (sphincter urethrae)

Bulbourethral (Cowper’s) glands

Deep transverse perineal muscles

Internal pudendal vessels and branches

Dorsal nerves of the penis

What are the contents of the deep perineal space in females?

Part of the urethra

Part of the external urethral sphincter

Part of the vagina

Branches of the internal pudendal vessels

Branches of the pudendal nerve

What is the ischioanal fossa (ischiorectal fossa) and what does it contain?

Wedge-shaped space on each side of the anal canal

- Dense fat (supports anal canal, allows distension during defecation)

- Pudendal nerve and internal pudendal vessels in a fascial canal

- Inferior rectal nerve and vessels crossing the fossa to the anal canal

Where is the pudendal canal located?

On the lateral wall of the ischioanal fossa,

On the medial side of the ischial tuberosity

What are the contents of the pudendal canal?

Pudendal nerve

Internal pudendal artery

Internal pudendal vein

Enumerate the muscles involved in avulsion fracture of the Anterior Superior Iliac Spine (ASIS).

Sartorius muscle and tensor fasciae latae muscle

Enumerate the muscles involved in avulsion fracture of the Anterior Inferior Iliac Spine (AIIS).

Rectus femoris muscle

Enumerate the muscles involved in avulsion fracture of the Ischial Tuberosity.

Hamstring muscles and portion of the adductor magnus muscle

Enumerate the muscles innervated by the pudendal nerve.

External anal sphincter

External urethral sphincter

Ischiocavernosus muscle

Bulbospongiosus muscle

Superficial transverse perineal muscle

Enumerate the muscles that form the pelvic diaphragm.

Paired levator ani muscles

Coccygeus muscle

Enumerate Parts of the Os Coxae (Hip bone)

Ilium

Ischium

Pubis

Enumerate Parts of the Bony Pelvis

Paired Hip Bone (Ox Coxae)

Sacrum

Coccyx

Enumerate Parts of the Levator ani muscle

Puborectalis

Pubococcygeus

Iliococcygeus

Enumerate Parts of the Vulva

Mons Pubis

Labia Majora

Labia Minora

Clitoris

Vestibule

Vestibular Bulbs

Greater Vestibular Glands

Enumerate Parts of the Lateral Pelvic wall

Hip Bone

Obturator Membrane

Sacrotuberous Ligament

Sacrospinous Ligament

Obturator Internus Muscle

Obturator Fascia

Enumerate Parts of the Posterior Pelvic wall

Sacrum

Coccyx

Piriformis Muscle

Parietal Pelvic Fascia

Enumerate Parts of the Anterior Pelvic wall

Bodies of Pubic Bones

Superior and Inferior Pubic Rami

Pubic Symphysis

Enumerate Structures that opens onto the Vestibule of the Female vulva

External Urethral Orifice

Vaginal Orifice

Duct of Greater Vestibule (Bartholin's Gland)

Duct of Lesser Vestibule (Skene's Gland)

Enumerate Muscles involved in the mechanism of penile and clitoral erection

Ischiocavernosus Muscle

Bulbospongiosus (Bulbocavernosus) Muscle

Supporting Pelvic Muscles involved in the mechanism of penile and clitoral erection

Superficial transverse perineal muscle

Deep transverse perineal muscle.

Enumerate Hormones involved in Relaxation of the Pelvic joints and Pelvic Ligaments during Childbirth

Estrogen & Progesterone produced by ovary and placenta.

Superior Gluteal Nerve distribution

Gluteus medius

Gluteus minimus

Tensor Fasciae Latae muscles

Inferior Gluteal Nerve distribution

Gluteus Maximus Muscle

Nerve to Piriformis distribution

Piriformis Muscle

Nerve to Obturator Internus distribution

Obturator internus

Superior gemellus muscles

Nerve to Quadratus Femoris distribution

Quadratus femoris

Inferior Gemellus muscles

Perforating Cutaneous Nerve distribution

Skin over medial aspect of the buttock.

Posterior Cutaneous Nerve of the Thigh distribution

Skin over posterior surface of the thigh & popliteal fossa

Lower part of the buttock, scrotum, or labium majus.

Sciatic Nerve (L4-L5; S1-3), Tibial Portion distribution

Hamstrings muscles (semitendinosus, biceps femoris (long head)

Adductor magnus (hamstring part)

Gastrocnemius

Soleus

Plantaris

Popliteus

Tibialis posterior

Flexor digitorum longus

Flexor hallucis longus, and via medial and lateral plantar branches to muscles of sole foot

Common Fibular (Peroneal) Portion distribution

Biceps femoris muscle (short head) and via deep fibular branch:

◦ tibialis anterior

◦ extensor hallucis longus

◦ extensor digitorum longus

◦ fibularis tertius

◦ extensor digitorum brevis muscles

- Skin over the cleft between the 1st & 2nd toes.

- The superficial fibular branch supplies the fibularis longus and brevis muscles and the skin over the lower third of anterior surface of the leg and the dorsum of the foot.

Pudendal Nerve distribution

Muscles of the perineum including the external anal sphincter

Mucous membrane of the lower half of the anal canal

Perineal skin

Skin of the penis

Scrotum

Clitoris

Labia majora and minora

Enumerate 4 Blood vessels which enters the Pelvic cavity through the Pelvic inlet

Internal Iliac Artery

Superior Rectal Artery

Ovarian Artery

Median Sacral Artery

Supports upper part of the vagina

Levatores ani muscles

Transverse cervical

Pubocervical

Sacrocervical ligaments

Supports the middle part of the vagina

Urogenital diaphragm

Supports the lower part of the vagina

Perineal body

Enumerate Structures that supports the Uterus

Transverse Cervical (Cardinal / Mackenrodt's) Ligaments

Pubocervical Ligaments

Sacrocervical (Uterosacral Ligaments

Enumerate Layers of the Uterus

Myomterium

Endometrium

Parametrium (book) or Perimetrium (internet)

Enumerate Parts of the Broad ligament

Mesometrium

Mesosalpinx

Mesovarium

Borders of the Ischioanal fossae (Base, Apex, Medial Wall, Lateral Wall, Posterior Extension, and Anterior Extension)

Base: Skin (superficial)

Apex: Junction of the medial and lateral walls.

Medial Wall: Sloping levator ani muscle and the anal canal.

Lateral Wall: Lower part of the obturator internus muscle, covered with pelvic fascia.

Posterior Extension: A posterior recess extending deep to the gluteus maximus muscle.

Anterior Extension: An anterior recess extending forward between the perineal membrane and the pelvic diaphragm.

Borders of the Pelvic inlet (Lateral, Posterior and Anterior)

Lateral Border : Iliopectineal lines

Posterior Border : Sacral promontory

Anterior Border: Symphysis Pubis

Borders of the Pelvic outlet (Posterior, Lateral, and Anterior)

Posterior: coccyx

Lateral: ischial tuberosities

Anterior: pubic arch

Borders of the Perineum (Anterior, Anterolateral, Lateral, Posterolateral, Posterior)

Anterior border: Symphysis pubis

Anterolateral borders: Ischiopubic rami (inferior pubic rami + ischial rami)

Lateral borders: Ischial tuberosities

Posterolateral borders: Sacrotuberous ligaments

Posterior border: Tip of the coccyx

An imaginary line joining the two ischial tuberosities divides the perineum into

Urogenital triangle (anterior)

Anal triangle (posterior)

Borders of the Urogenital triangle (Anterior, Lateral, Posterior, Apex)

Anterior border: Pubic symphysis (pubic arch)

Lateral borders: Ischiopubic rami (inferior ramus of pubis + ramus of ischium)

Posterior border (base): Imaginary line joining the two ischial tuberosities

Apex is directed anteriorly toward the pubic symphysis

Borders of the Anal triangle (Anterior, Lateral, Posterior)

Anterior border (base): Imaginary line joining the two ischial tuberosities

Lateral borders: Sacrotuberous ligaments, overlapped by fibers of gluteus maximus

Posterior border (apex): Tip of the coccyx

The anus lies in the midline; an ischioanal fossa is present on each side.

Borders of the Vestibule (Anterior, Posterior, Lateral)

Anterior border (apex): Clitoris

Posterior border (base): Fourchette (frenulum of labia minora)

Lateral borders: Labia minora

Homologue structures – Clitoris

Female phallic organ that corresponds to the penis in the male. It is situated anteriorly, at the apex of the vestibule. Its structure is similar to that of the penis.

Homologue structures – Greater Vestibular Glands

Pair of small mucus-secreting glands that lie under cover of the posterior parts of the bulbs of the vestibule. Each drains its secretion into the vestibule by a small duct, which opens into the groove between the hymen and the posterior part of the labium minus. These glands secrete lubricating mucus during sexual intercourse. The greater vestibular glands are the homologues of the male bulbourethral glands.

Homologue structures – Lesser Vestibular (Paraurethral) Glands

The _________ lie on each side of the vestibule. They open into the vestibule by small ducts on either side of the external urethral orifice. These glands correspond to the prostate in the male.

Average length of Male urethra

8 in. (20 cm)

Average length of Female urethra

1.5 in. (3.8 cm)

Average length of Anal canal

1.5 in. (4 cm)

Minimum volume of urine necessary to stimulate micturition reflex

300 mL

Muscles that cover the Crura of Penis and Crura of Clitoris?

ischiocavernosus muscle

Muscles that cover the Penile bulb and Vestibular bulb?

bulbospongiosus muscle

Erectile tissue of the Crura of Penis and Crura of Clitoris?

corpora cavernosa

Erectile tissue of the Penile bulb and Vestibular bulb?

corpus spongiosum

Fascia that encloses the erectile tissues contained within the body of the penis

Tubular sheath of deep fascia (Buck's fascia)

Structure which separates the Superficial perineal pouch from the Deep perineal pouch

Perineal membrane

Upper part of the Anal Canal, it is lined by

columnar epithelium

Lower part of the Anal Canal, it is lined by

stratified squamous epithelium